CN113825585B - Method and apparatus for laser processing of transparent materials - Google Patents

Abstract

The present invention relates to the production of transparent materials by ultrashort laser pulses. A method for producing a material that is mostly transparent to laser wavelengths, the method comprising forming a non-centrosymmetric non-diffraction beam from an optical element, the optical element containing at least two birefringent structure regions, the birefringent structure region according to a specific The rules in that particular area change the Pancharatnam‑Berry phase. The distribution of energy, phase and polarization depends on the parameters of the light approaching the element. The pulse energy is chosen to exploit the main maximum of the distribution to form voids that are elongated in the desired direction, while the side maxima form changes in chemical properties between lesions from adjacent pulses. Areas of void damage and chemical changes form the desired cut line. The workpiece prepared in the described manner is placed in a chemical aggregation solution, in which the areas affected by the laser dissolve much faster than the unaffected areas. This enables cuts with aspect ratios up to 1/50.

Description

Method and apparatus for laser processing of transparent materials

Technical field

The invention belongs to the field of laser and relates to the processing of transparent media, and can be used for cutting, splitting and other processing of transparent media, including different types of glass, chemically tempered glass, sapphire and Other crystalline materials.

Background technique

To cut holes of very small dimensions or to create free-form cuts in workpieces of transparent materials, laser methods are used. Conventional laser micromachining (drilling, cutting or groove forming, etc.) methods often rely on the removal of material due to the focus of the laser pulse energy in the affected area - ablation. Femtosecond lasers are used for this purpose to produce very clean edges of holes or cuts, and there is virtually no material that cannot be processed by this laser. However, ablation has a fundamental disadvantage - it is impossible to remove material from very narrow gaps or small diameter holes, since the material removed from the bottom of the cut accumulates on the wall above the affected area, gradually covering the entrance of the light. This disadvantage is avoided by using splitting separation, where the laser pulse creates a damaged area along the desired splitting line. However, this method is very limited when splitting the workpiece along lines of high curvature, especially when drilling is required. The task becomes more complex when the workpiece is made of glass, especially if the glass is tempered. Glass has recently become increasingly important as a material used in semiconductor technology (as the basis for semiconductor structures), the fabrication of microelectromechanical systems, and the fabrication of microfluidic devices. All of these areas require the ability to create cuts, holes or channels of any shape. More recently, laser methods have been used in combination with chemical etching, which has greatly expanded the capabilities of these methods.

Known analogues use acid or alkali etching of the material affected by laser light. US20180029924A1 describes a method in which UV laser drilled holes are etched with HF acid, taking advantage of the property that material affected by the laser etch faster than unaffected material. The holes obtained in this way have different diameters (usually hourglass-shaped) throughout the thickness of the workpiece, and during etching the holes expand evenly in all directions; during etching the entire cut line this results in holes with The spacing between the cuts is almost the same width.

The method proposed in US2018037489 also exhibits no orientation, with the hole penetrated by the laser expanding evenly in all directions during etching. This method is not intended for making cuts or grooves, but only for circular holes.

US9517963B2 describes a method using uniform widening of laser perforations by etching. In this method, a centrally symmetric, non-diffracted Bessel beam is used to pierce the glass, so the hole is circular and non-directional. This method does not offer the option of etching uniform cuts, it only facilitates the splitting of the workpiece along the lines connecting the holes. By using the described method, significant slopes are obtained at the entrance and exit of the holes in the workpiece, i.e. the holes deviate significantly from the cylindrical shape, which also results in cuts with irregularly shaped slopes. Additionally, when perforated with a laser, micro-cracks form in unpredictable shapes around them, and as the glass-etching acid diffuses through them, it enlarges the holes while reducing the smoothness of the cracks. Due to the random nature of the cracks, the cracks are Smoothness is uneven along the split line.

EP3102358A4 describes a method that utilizes etching of laser perforations to enlarge the holes and for the purpose of breaking glass using the holes along the contour formed by the holes. The orientation of the etching process is neither sought nor controlled, and the holes are not connected.

US20160152508A1 describes a method for separating glass workpieces along the lines of laser-made and etched enlarged holes. The orientation of the etching process is neither sought nor controlled, and the holes are not connected.

Using the combined laser and chemical processing methods described above, it is possible to create glass holes in sheets of glass of sufficient thickness to achieve a glass thickness to diameter ratio of 20-30 or greater. Their main problem is that after etching the affected glass with corrosive acids or their mixtures such as HF, BHF, HF+HNO ₃ , the shape of the resulting holes deviates significantly from the barrel (e.g. "hourglass"), and their The edges are not straight but have a significant slope of 5%-10% of the diameter. This is unacceptable for most applications. When the affected glass is etched with alkali such as NaOH or KOH, the geometry of the holes is much more precise than when using acids, but the process itself is quite slow, taking several hours to etch a gap a few microns long.

Technical issues to be resolved

The purpose of the present invention is to improve the processing quality of transparent materials while improving the processing accuracy when splitting or cutting transparent materials.

Contents of the invention

In order to solve the problem according to the invention, a method of processing transparent materials by forming cutting surfaces or splitting surfaces in the workpiece material is proposed, which method consists of two processing stages:

- Stage A, in which stage A cutting or splitting surface formation with a laser is performed without complete separation of the workpiece parts from each other, wherein stage A includes the following steps:

A.1 laser produces a coherent ultrashort pulse laser radiation beam in TEM ₀₀ mode,

A.2 directing the generated laser radiation beam into an optical system that shapes the set diameter, total pulse energy and light polarization of the laser radiation beam,

A.3 guide the laser radiation beam formed in step A.2 into an optical element that transforms the incident laser radiation beam according to predetermined rules,

A.4 Position the formed laser radiation beam in the workpiece, the material of the workpiece is almost transparent to the laser beam radiation, and the predetermined parameters of the laser radiation pulse ensure that the laser radiation energy is in the focused area of the processed workpiece Density is enough to change the properties of the workpiece material,

A.5 Make the machined workpiece controllably move relative to the laser radiation beam, so that the focus of the laser radiation beam in the workpiece is respectively shifted, thereby creating the required number of damage areas and in the workpiece Form the desired trajectory of cutting and/or splitting the surface,

- Phase B, in which the complete separation of the workpiece parts from each other is performed by placing the workpiece in a chemical medium, which is located in the damaged area, based on the trajectory of the cutting surface and/or splitting surface formed during stage A Etching the workpiece material at , where,

In step A.3, a transformation of the laser radiation beam according to predetermined rules takes place in an optical element (10) which includes a birefringence that smoothly changes the Pancharatnam-Berry phase (PBP) of the vertical laser radiation beam. Structure, wherein at least two regions of said structure are formed in an optical element (10) with different PBP transformation rules and with orientations close to the element with respect to the laser radiation beam, wherein at least two of said structural regions each form at least Two sub-beams, the at least two sub-beams being able to change the energy, phase and polarization distribution of the sub-beams according to parameters of the laser radiation close to the optical element (10) such as polarization type, the polarization type represents linear or circular or radial or azimuthal The orientation of the angular, and/or linear polarization planes relative to the direction of the cutting or splitting tracks in the element, where,

The formed sub-beams interfere with each other to obtain a total non-diffracted laser radiation beam having an eccentrically symmetrical distribution of set energy, phase and polarization focal line perpendicular to the laser beam. Better elongation in the plane of the direction of propagation of the radiation beam, wherein the desired form of the above distribution can be obtained by changing the parameters of the laser radiation formed during step A.2 close to the optical element (10), where The eccentrically symmetric distribution of the non-diffracted laser radiation beam has in the vertical plane of light propagation a main rectangular energy maximum and a secondary energy maximum, the main rectangular energy maximum containing most of the energy of the pulse with density ρ, and this secondary energy The maximum is elongated in said plane, where the energy density is between ρ/6 and ρ/3,

The total laser radiation beam obtained is positioned in the workpiece, wherein each laser radiation pulse forms an elongated general damage zone consisting of physical and chemical changes due to the influence of said principal energy maximum The resulting cavities and/or cracks are formed by chemical changes in the workpiece material due to the influence of said sub-energy maxima, wherein said optical element (10) surrounds said optical element (10) ) axis and moves the machined workpiece in a controlled manner so that the elongated damage areas formed due to physical changes in the workpiece material are formed one after another in the longitudinal direction and along the cutting trajectory and/ or split trajectories are positioned in such a way that they have gaps,

In steps A4 and A5, the laser pulse energy and power and the workpiece movement speed are selected so that the damage area formed due to the chemical change of the workpiece material extends along the cutting trajectory to such that the damage area that appears due to the physical change of the damage extends The degree to which adjacent common damage areas merge or overlap; and in stage B, the chemical medium will act on the workpiece material simultaneously along the entire cutting trajectory.

The resulting elongated common damage area lies in an elliptical plane perpendicular to the direction of light propagation and has an approximately constant size that varies no more than +/-15% from the mean value along said direction.

The trajectory of the cutting surface or splitting surface is formed from the elongated common damage area by propagating one or more undiffracted beams along the trajectory of the cutting surface or splitting surface at a distance comparable to the lateral dimensions of the beam.

Elongated lesions caused by physical changes in the workpiece are arranged with steps exceeding the width of the lesion by at least 1.5 times.

In step B, the workpiece is immersed in several selected chemically active liquids such as KOH solution, Na ₂ CO ₃ solution, HF solution, HCl solution in order to remove the products of previous chemical reactions formed and retained in the damaged area of the workpiece. Transfer and dissolve in another solution affecting the workpiece.

According to another embodiment of the present invention, a device for processing transparent materials is proposed, the device includes a laser, a controllable positioning mechanism, and a container, wherein the laser generates ultrashort pulse laser radiation TEM ₀₀ mode (2) of the beam and directed to an optical system for changing the pulse energy, light polarization and diameter of the laser radiation beam, whereby the laser radiation beam formed in the optical system is positioned at In the processed workpiece, whereby the workpiece material is almost transparent to the laser radiation beam, the selected laser radiation beam pulse parameters formed in the optical system ensure that the laser radiation energy density is sufficient to change the properties of the workpiece material in the focused area. Nature, the controllable positioning mechanism is used to move the processed workpiece relative to the laser radiation beam, so that the focus of the laser radiation beam in the workpiece moves, thereby generating a required number of damage areas and forming a required cutting trajectory in the workpiece. or a split surface, a container containing chemical media that etch the workpiece material in the damaged area, and the container is intended to house the workpiece in the container and to move parts of the workpiece to each other according to the trajectory formed by the cutting surface and/or the splitting surface separation, among which,

Optical elements located outside the optical system in the path of the laser radiation beam and intended to transform the incident laser radiation beam according to predetermined rules have a birefringent structure that homogenizes the Pancharatnam-Berry phase (PBP) of the vertical laser radiation beam , whereby at least two regions of birefringent structures with different PBP transformation rules and with an orientation relative to the laser radiation beam approaching the element are located in the workpiece, wherein the regions of said structures form at least two interfering sub-beams It is used to generate a total non-diffracted laser radiation beam. The total non-diffracted laser radiation beam has an eccentric symmetrical distribution of predetermined energy, phase and polarization focal line. The eccentric symmetrical distribution has better performance in a plane perpendicular to the propagation direction of the laser radiation beam. elongation and having a primary energy maximum and a secondary energy maximum, wherein the optical element is mounted on a mounting mechanism that rotates around the axis of the optical element for changing the position of the element and changing the birefringent structure formed in the element, The total undiffracted laser radiation beam formed by the element is positioned in the workpiece via focusing optics, whereby by rotating the optical element via said mechanism, the orientation of the resulting elongated common damage zone along the trajectory of the cutting line is determined Change, and the controllable positioning mechanism moves the workpiece such that the elongated damage areas formed due to physical and chemical changes in the workpiece material are formed one after another in the longitudinal direction and along the cutting trajectory and/or splitting trajectory Arranged so that the elongated damage areas formed due to physical changes in the workpiece material and with gaps along the cutting trajectory and/or splitting trajectory are positioned one after another in the longitudinal direction, and such that due to chemical changes in the workpiece material The formed damage area extends the damage area that appears due to the physical change of the damage along the cutting trajectory to the extent that adjacent common damage areas merge or overlap.

Advantages of the present invention

The proposed laser chemical treatment method for workpieces allows obtaining precise geometric cuts or holes in a period of time that is 10 times faster than the known laser-assisted chemical etching (LACE) or laser-induced chemical etching (LICE) methods Or more.

The proposed invention makes it possible to etch laser-formed narrow bonding lines of physically and chemically oriented damaged areas. In the present invention, overall damage occurs due to changes in the structure of the workpiece material involving the formation of pores, self-aligned structures, mechanical stress, and chemical changes involving the rearrangement of chemical bonds or the formation of free bonds.

In the proposed method, physical damage occurs to the rectangular cross-section beam at the highest strength point (up to the perforation of the hole), and the lower strength area expands in the direction of the cut line and changes the chemical properties of the material. By achieving a cutting width to depth ratio of up to 1:100 without deviating from the vertical axis by more than 2° and maintaining a cutting slope of no greater than 0.1 μm, the resulting total damage area improves machining accuracy. The surface irregularities of the etching cuts should not exceed 2 μm, their slopes should not exceed 0.1 μm, and the cuts should not have overlaps. Therefore, products manufactured using this method can be used in applications that require high precision and verticality, such as guide spacers for semiconductor device test boards, which significantly extends their service life.

The absence of slope and overlap allows the use of products for planar bridging without the need for additional polishing after chemical processing, which accelerates the production of microelectromechanical systems (MEMS) and microfluidic devices.

Description of the drawings

The invention will be explained in more detail in the following figures, which do not limit the scope of the invention and include:

Figure 1 shows part of a schematic block diagram of the proposed transparent material processing device, which explains the formation of the laser beam before entering the optical elements that form the distribution.

Figure 2 shows a part of a schematic of the proposed transparent material processing device, showing how the desired distribution is formed and how it is positioned in the processed workpiece.

FIG. 3 shows the coordinates of the birefringent structure formed in the beam conversion element in the polar coordinate system and the Cartesian coordinate system.

Figure 4 shows areas of PBP variation in elements arranged in sectors.

Figure 5 shows the area of PBP variation in concentrically arranged elements.

Figure 6 shows the most common arrangement of PBP variation zones in a component, where the PBP variation in different sectors also depends on the distance of the birefringent structure from the center of the component.

Figure 7 shows the specific case where the PBP transformation in two 180° sectors has different dependence on the distance from the center.

Figure 8 shows the measured lateral energy distribution generated by the elements from Figure 7.

Figure 9 shows the variation of the energy distribution of Figure 8 along the light propagation direction.

Figure 10 shows a controlled direction damage line obtained by rotating the element about the axis of the light beam.

Figure 11 shows damage to this wire, where the fields of physical (puncture) and chemical (bond rearrangement) damage are identified.

Figure 12 shows the structure of the most common alkaline earth aluminosilicate glass.

Figure 13 shows the cutting edge profile measured by atomic force microscopy (AFM).

Detailed ways

The proposed method for processing transparent materials consists of the following sequence of operations:

The transparent material processing method has two processing stages:

Cutting or splitting surface formation with the laser is performed during stage A without complete separation of the workpiece parts from each other. Phase A consists of the following steps: A.1 - Generate a beam of coherent ultrashort pulsed laser radiation in the TEM ₀₀ mode by the laser. A.2 - Direct the generated laser radiation beam into an optical system that forms the set diameter, total pulse energy and light polarization of the laser radiation beam, A.3 - Direct the laser radiation beam formed in step A2 into The optical element transforms the laser radiation beam according to predetermined rules. This transformation occurs in an optical element where a birefringent structure is formed that uniformly changes the Pancharatnam-Berry phase (PBP) of a laser beam aimed perpendicularly to the birefringent structure. At least two regions of the structure are formed in the optical element and have different PBP variation rules and have their orientation relative to a laser beam aimed perpendicularly to the birefringent structure. At least two of said regions of the structure respectively form at least two sub-beams, with parameters such as polarization type (such as linear or circular or radial or azimuthal) according to the parameters of the light aimed at said optical element and/or relative to the element. The possibility to change the distribution of sub-beam energy, phase and polarization by orienting the linear polarization plane in the direction of the cutting trajectory or splitting trajectory. The formed sub-beams interfere with each other to obtain a total non-diffracted laser radiation beam having an eccentrically symmetric distribution of set energy, phase and polarization focal line, emitted perpendicular to the laser radiation beam With better elongation in the plane of the direction, the desired form of the above-mentioned distribution can be obtained by changing the parameters of the laser radiation formed during step A.2 aimed at the optical element. The polymerized laser radiation beam obtained in step A.4 is positioned in the workpiece, where each laser radiation pulse forms a rectangular total damage area consisting of physical and chemical changes in the workpiece material. The material of the workpiece in which the laser radiation beam is positioned is mostly transparent to the laser radiation beam, and the set parameters of the laser radiation pulse ensure that the laser radiation energy density in the focal area of the processed workpiece is sufficient to change the properties of the workpiece material. In step A5, by rotating the optical element about its axis, the total damaged area in the workpiece is oriented along the cutting trajectory and/or the splitting trajectory, and the machined workpiece is moved in a controlled manner such that the elongated shape formed The damaged areas position themselves one after the other and with gaps along the cutting and/or splitting trajectories. The laser pulse energy and power and the workpiece movement speed are selected so that the damage area formed due to chemical changes in the workpiece material will extend along the cutting trajectory such that adjacent common damage areas merge or degree of overlap. The resulting elongated common damage area is preferably in an elliptical plane perpendicular to the direction of light propagation and has an approximately constant size that varies no more than +/-15% from the mean value along said direction . The trajectory of the cutting surface or splitting surface is formed from the elongated common damage area by propagating one or more undiffracted beams along the trajectory of the cutting surface or splitting surface at a distance comparable to the lateral dimensions of the beam. Elongated lesions caused by physical changes in the workpiece are arranged with steps exceeding the width of the lesion by at least 1.5 times.

Next, based on the trajectory of the cutting surface and/or splitting surface formed during stage A, a complete separation of the workpiece parts from each other is performed during stage B by placing the workpiece in a chemical medium to etch the workpiece material at the damaged area. Since the common damage areas formed along the cutting trajectory or slit trajectory are adjacent or overlapping, the chemical medium affects the workpiece simultaneously on the entire cutting surface trajectory or split surface trajectory, and the affected workpiece material in this trajectory is larger than the unused material of the workpiece. The affected parts dissolve much faster. After keeping the workpiece in solution for the desired period of time, the reagent dissolves the workpiece material along the cut line so that it extends slightly perpendicular to the line, and the parts of the workpiece separate from each other. The chemical medium in which the workpiece is placed after treatment with the laser radiation beam in stage A can be a solution of KOH, but it is better to place the workpiece successively in several chemically active liquids such as KOH solution, Na ₂ CO ₃ solution, HF solution and HCl in solution. After the workpiece is removed from one chemical media solution, it is placed in another chemical media solution that dissolves the products of previous chemical reactions that have formed and remain in the damaged areas of the workpiece. In this way, the workpiece is placed in solutions of different chemical media until parts of the workpiece are separated from each other very precisely without any transverse cracks.

Laser (1) is used in the proposed way for the splitting of transparent materials, (Fig. 1) generating ultra-short (100 fs-10 ps duration) light pulses of TEM ₀₀ mode, which have in cross section (2) described by the Gaussian formula energy distribution

where I(r) is the light intensity at a point on the beam at a distance r from the beam axis, l(0) is the light intensity on the beam axis, and ω ₀ is the distance from the axis to where I(r) = I(0) /e distance from the point.

The light intensity in the beam is controlled by an adjustable attenuator (3) consisting of a half-wave plate (4) and a polarizer (5) whose polarization plane is adapted to All light from the laser is passed without a half-wave plate (4) in the path. By rotating the direction of the slow axis of the plate relative to the polarization plane of the laser, the polarization direction of the light passing through the plate is rotated accordingly, and when the polarizer (5) only passes the light component parallel to the polarization of the light emitted by the laser , can allow 0% to 100% of the light from the laser to pass, depending on the steering angle of the half-wave plate (4).

The diameter of the beam passing through the attenuator is set by an adjustable expander (6) consisting of a set of negative lenses (7) and positive lenses (8). By adjusting the distance between the lenses, the desired diameter of the beam leaving the expander can be obtained.

If it is necessary to have an elliptically polarized beam, a quarter-wave plate (9) is placed in its path, the angle of its slow axis with the plane of polarization of the light aimed at it sets the ellipticity and direction of rotation of the circular polarization ( left or right).

An optical element (10) made of a flat workpiece of transparent material is placed in the path of the laser beam, and in this optical element (10) a structure is formed that changes the Pancharatnam-Berry phase (PBP) of the light.

The diameter of the laser beam is chosen such that the beam completely fills the working area of the beam forming element. This means that the light intensity at a distance _RE from the beam axis must not be greater than I( _RE )≤I(0)/e ² , in other words, the element radius must not be smaller than the Gaussian beam radius in equation [1] twice, that is,

R _E ≥2ω ₀ [2]

By placing a beam-forming optical element (10) with a PBP of varying cross-section into the laser beam (11), the polarization plane is rotated according to predetermined rules at different positions in the element and the desired phase retardation is introduced. The element is mounted on a rotation mechanism (12) which makes it possible to change the position of the element and at the same time the position of the structures recorded thereon relative to the polarization plane aimed at the element. The beams (13) emanating from various parts of the element interfere with each other in a constructive and destructive manner, allowing the desired distribution of energy, phase and polarization (14) to be formed. The resulting distribution with shape (18) is transferred into the workpiece (19) via focusing optics (15, 16, 17). At least part of the focusing optics forms a 4f scheme that is used to add additional amplitude functions to the Fourier plane such as filtering out unwanted amplitude spectral elements while creating a desired distribution in the focal line. The position of the focus area on axis Z is determined by a height adjustment mechanism (20), and the workpiece itself can be moved in the X-Y plane by a positioning mechanism (21).

In the optical element (10), one or more zones are formed, in each zone the Pancharatnam-Berry phase (PBP) varies smoothly according to the set of rules for that zone.

At each point of the cross-section, the PBP value is set by the periodic nanoplate structure (23) formed in the workpiece body (Fig. 3), whose orientation in the element is determined by the correlation in Cartesian coordinates describe sex

θ _i =f _i (x _i , y _i ) [3]

Among them, θi is the steering angle of the periodic structure relative to the coordinate axis in the i-th region, which is described by the function fi.

Or in polar coordinates:

here and/> are the polar coordinates of this periodic structure in the cross-section of the element.

In order to obtain a distribution with axial symmetry (circular or elliptical), these areas can be arranged in two sectors (Fig. 4).

where, R _E is the radius of the element, are the starting and ending angles of the sectors in polar coordinates, respectively.

Two concentric rings (Figure 5)

where r _min,i and r _max,i are the values of the starting radius and the ending radius of a ring or rings divided into sectors (Fig. 6).

In separate specific cases, where sectors and/> Two regions are formed in the element of , the changes in PBP are formed in each sector by rings, and in each ring the PBP changes are described by a function specific to that ring (Fig. 7):

Among them, θ _ij , are the PBF in the n-th sector and the orientation angle of ring i or j, where i and j are the ring numbers in the 1st or 2nd sector respectively (Fig. 7). If the function is selected as follows:

as well as

where r _e is the radius of the element and a is the factor that determines the convergence angle of the sub-beams.

The PBP element forms a non-diffracted beam.

By placing an optical element (10) described by functions [9] and [10] in the laser beam, an elliptically symmetric distribution is formed behind the element (Fig. 8) with one or more maximum maxima in the direction of light propagation. value (Figure 9). The intensity distribution between maxima is determined by the nature of the polarization (linear, circular or elliptical) of the light aimed at the element. A main maximum (24) is formed in this distribution, in which most of the beam energy is concentrated, and an elliptical secondary maximum (25) is also formed around this distribution. The direction of the longitudinal axis (26) of the distribution ellipse (Fig. 8) depends on the orientation of the sectors of the element in a plane perpendicular to the direction of light propagation.

By focusing the distribution generated by the element in the glass and after the pulse power density exceeds the limit ρ _rib , the value of which depends on the composition of the glass, hollow damage areas are formed in the glass body, the shape of which mimics the intensity in the focused area distributed. For example, borosilicate glasses have high (~6%-10%) alkaline earth content, i.e., ρ _rib ≈1×10 ¹⁵ Wcm ^-3 , whereas in glasses without alkaline earth elements, this limit It is ρ _rib ≈5×10 ¹⁴ Wcm ^-3 . The energy distribution is formed in such a way that ρ _rib will only be exceeded at the main maximum (24).

The glass workpiece (19) is moved in the XY plane perpendicular to the light propagation direction, and at the same time an elliptical damage area (27) is arranged. The elliptical damage area (27) is changed by the rotation mechanism (12) to change the longitudinal axis of the distribution ellipse. position along the desired cutting line (28). This particular glass is characterized by the chemical changes that occur when the power density ρ of the elliptical submaxima (25) overlapping adjacent pulses exceeds the splitting occurrence threshold ρ _sk =ρ _rib /6 _÷ ρ _rib /3 (29) (Fig. 10) also results in the occurrence of physical stress and the incorporation of areas of physical damage.

Areas of altered physicochemical properties of the glass form around the damaged area (30, Figure 11). Glass is a network of oxide structures in which alkali metal ions and/or alkaline earth metal cations are mixed. In individual cases, aluminosilicate glasses with an Al/Si content ≥1/3 (Fig. 12) are composed of oxygen atom tetrahedrons with silicon (31) atoms or aluminum (32) atoms in the center. The vertices of some of these tetrahedrons are connected by bridging oxygen (BO) bridges. The bond types of bridging oxygen (BO) bridges are classified as BO1 (33) connecting Si-O-Si tetrahedrons and connecting Si-O-Al tetrahedra. Body BO2(34). The free oxygen atoms in the corners are called non-bridging oxygen (NBO) (35). Between these relatively ordered structures, cations of alkali metals (AM, 36) and alkaline earth metals (EM, 37) are relatively freely intercalated, and the presence of these cations affects the formation of oxygen bridges and the ratio of BO1/BO2 bridge amounts . It is known that when the atomic weight AM/Al≈1, the ratio of the amounts of different types of bridges is BO2/BO1≈3, NBO/BO2=0, while in a glass workpiece with AM/Al≈0.2, the ratio BO2/ BO1≈0.3, and non-bridging oxygen bonds NBO/(BO1+BO2)≈0.1 were also observed.

When laser pulses affected this glass workpiece, significant changes in the BO/NBO ratio were observed. It has been established that in most glasses, after the laser pulse energy density exceeds 2 × 10 ³ J/cm ² , the ratio reaches BO/NBO ≈ 0.3, i.e., when compared with the glass unaffected by the laser, the BO bridge The amount was reduced by more than ~3 times. When the glass is affected by the laser, BO-type bridges break and form with excess silicon or aluminum (ODC I) ≡Si-Si≡ and ≡A1-A1≡ or with free bonds (ODC II)=Si ⁰ ir=A1 ⁰ Oxygen Hypoxia Center (ODC). There are also non-bridging oxygen hole centers (NBOHC) such as ≡Si-O ^° or ≡A1-O ^° formed in the structure. All these defects are significantly more chemically active than unaffected glass, such that when the affected workpiece is placed in an alkaline solution, hydroxyl anions react with the opened bonds and form soluble products such as:

[-Si-O-Si-]+OH ^- [-SiO] ^- +[-Si-OH] [11]

[-Al-O-Al-]+OH ^- →[-AlO] ^- +[-Al-OH] [12]

The network-modified alkaline earth metal (Ca, Mg, Ba, Zn) oxides formed when metals combine with free oxygen do not react directly with alkali, but are soluble in alkali. At the same time, alkali metals (Li, Na, K) enter the solution in the form of hydroxides.

As a result of the process described above, the area of the glass affected by the secondary maximum of the pulse dissolves in the alkali up to 1000 times faster than the unaffected area. This means that by creating areas with high levels of free oxygen or reactive silicon and aluminum bonds in the desired cut line, the alkali will essentially only dissolve the cut area without touching the workpiece material, which does not need to be removed. This results in extremely high-precision cutting. As can be seen from Figure 13, only a slope of 0.05 μm-0.1 μm (50 nm-100 nm) is formed on the edge of the cut.

Claims (7)

1. A method for processing transparent materials by forming cutting or splitting surfaces in the workpiece material, said method comprising two processing stages: - Stage A, in which stage A cutting or splitting surface formation by means of a laser is performed without complete separation of the workpiece parts from each other, wherein said stage A comprises the following steps: A.1 laser generates a coherent ultrashort pulse laser radiation beam in TEM ₀₀ mode, A.2 directing the generated laser radiation beam into an optical system that shapes the set diameter, total pulse energy and light polarization of the laser radiation beam, A.3 directing the laser radiation beam formed in step A.2 into an optical element, wherein the optical element transforms the incident laser radiation beam according to a predetermined rule, A.4 Position the formed laser radiation beam in the workpiece, the material of which is almost transparent to the laser beam radiation, and the predetermined parameters of the laser radiation pulse ensure that the laser radiation in the focused area of the processed workpiece The radiation energy density is sufficient to change the properties of the workpiece material, A.5 Make the machined workpiece controllably move relative to the laser radiation beam, so that the focus of the laser radiation beam in the workpiece is respectively shifted, thereby creating the required number of damage areas and in the workpiece Form the desired trajectory of cutting and/or splitting the surface, - a phase B in which, based on the trajectory of the cutting surface and/or the cleaving surface formed during phase A, a complete separation of the workpiece parts from one another is performed by placing the workpiece in a chemical medium, wherein the chemical medium etches the workpiece material at the damaged areas, It is characterized in that, in step A.3, the transformation of the laser radiation beam according to the predetermined rules occurs in the optical element (10), which includes the Pancharatnam-Berry phase (PBP) of the vertical laser radiation beam. ) undergoes a smoothly changing birefringent structure, wherein at least two elements forming the structure in the optical element (10) have different PBP transformation rules and have an orientation close to the element with respect to the laser radiation beam Region, wherein the at least two regions of the structure respectively form at least two sub-beams, the at least two sub-beams are capable of changing the energy, phase and polarization distribution of the sub-beams according to the polarization type, the polarization type represents linear or circular or radial or azimuthal, and/or the orientation of the linear polarization plane relative to the direction of the cutting or splitting trajectory in said element, where, The formed sub-beams interfere with each other to obtain a total non-diffracted laser radiation beam having an eccentrically symmetrical distribution of set energy, phase and polarization focal line, said eccentrically symmetrical distribution being perpendicular to Better elongation in the plane of the propagation direction of the laser radiation beam, wherein the desired form of the above-mentioned distribution can be obtained by changing the parameters of the laser radiation formed during step A.2 close to said optical element (10), wherein said eccentrically symmetrical distribution of said non-diffracted laser radiation beam has a main rectangular energy maximum and a secondary energy maximum in the vertical plane of light propagation, said main rectangular energy maximum containing a major part of the pulse with density p energy, and the sub-energy maximum is elongated in the plane with an energy density between ρ/6 and ρ/3, The total laser radiation beam obtained is positioned in the workpiece, wherein each laser radiation pulse forms an elongated general damage zone consisting of physical and chemical changes, the physical changes being determined by the main rectangular energy maximum The formation of cavities and/or cracks resulting from the chemical changes in the workpiece material resulting from the influence of the sub-energy maximum, wherein by surrounding the optical element (10) The axis of the optical element (10) rotates and moves the machined workpiece in a controlled manner, so that the elongated damage areas formed due to physical changes in the workpiece material are formed one after the other in the longitudinal direction. positioned with gaps along said cutting trajectory and/or said splitting trajectory, And in steps A4 and A5, the laser pulse energy and power and the workpiece movement speed are selected so that the damage area formed due to the chemical change of the workpiece material will be along the cutting area along the damage area due to the physical change of the damage. The trajectory extends to the extent that adjacent common damage areas merge or overlap; and in stage B, the chemical medium will act on the workpiece material simultaneously over the entire cutting trajectory. 2. The method of claim 1, wherein the formed elongated common damage area is located in an elliptical plane perpendicular to the direction of light propagation and has a constant size that varies from an average value along the direction. Start changing no more than +/-15%. 3. A method according to claim 2, wherein the elongated common beam is formed from the elongated beam by propagating more than one undiffracted beam along the trajectory of the cutting surface or splitting surface at a distance comparable to the lateral dimensions of the beam. The damaged area forms a trace of the cutting surface or the splitting surface. 4. The method according to claim 1 or 2, wherein the elongated damage caused by the physical change of the workpiece is arranged with a step that exceeds the width of the damage by at least 1.5 times. 5. The method according to claim 1 or 2, wherein in step B, the workpiece is sequentially immersed in several selected chemically active liquids so that the previous chemical reactions formed and retained in the damaged area of the workpiece The product is transferred and dissolved in another solution that affects the workpiece. 6. The method of claim 5, wherein the chemically active liquid is KOH solution, Na ₂ CO ₃ solution, HF solution and HCl solution. 7. A device for processing transparent materials, the device comprising: Laser (1), the laser (1) generates a beam of ultrashort pulse laser radiation TEM ₀₀ mode (2) and points to an optical system, the optical system is used to change the pulse energy, light polarization and diameter of the laser radiation beam, by This laser radiation beam formed in the optical system is positioned in the processed workpiece (19) via optical elements for transforming the incident beam according to predetermined rules, whereby the workpiece material is almost Transparent, the selected laser radiation beam pulse parameters formed in the optical system ensure that the laser radiation energy density is sufficient to change the properties of the workpiece material in the focused area, A controllable positioning mechanism for moving the processed workpiece relative to the laser radiation beam such that the focus of the laser radiation beam in the workpiece is moved to create a required number of damaged areas and at the desired location. the surface of the workpiece that forms the desired path of cutting and/or splitting, and A container containing a chemical medium that etches the workpiece material in the damaged area, and the container is intended to house the workpiece in the container and according to the cutting surface and/or splitting surface The resulting trajectory separates parts of the workpiece from each other, It is characterized in that an optical element (10) located outside the optical system in the path of the laser radiation beam and intended for transforming the incident laser radiation beam according to predetermined rules has a birefringent structure, said birefringent structure being vertical to The Pancharatnam-Berry phase (PBP) of the laser radiation beam is changed uniformly, whereby the birefringent structures are positioned in the workpiece with different PBP transformation rules and have proximity to the element with respect to the laser radiation beam At least two regions oriented, wherein the regions of the structure form at least two interfering sub-beams to produce a total beam of non-diffracted laser radiation having a predetermined energy, phase and polarization focus An eccentrically symmetrical distribution of lines with better elongation in a plane perpendicular to the propagation direction of the laser radiation beam and with a primary energy maximum and a secondary energy maximum, wherein the optical element (10) Mounted on a rotation mechanism that rotates around the axis of the optical element (10), used to change the position of the optical element (10) and change the birefringent structure formed in the optical element (10), consisting of the The total undiffracted laser radiation beam formed by an optical element (10) is positioned in the workpiece via focusing optics (15, 16, 17), whereby the optical element (12) is 10) Rotate, the orientation of the formed elongated damage area along the trajectory of the cutting line is changed, and the controllable positioning mechanism moves the workpiece, so that the workpiece material changes due to physical changes and chemical changes. The formed elongated common damage areas are arranged one after another in the longitudinal direction and along the cutting trajectory and/or the splitting trajectory, so that due to the physical changes of the workpiece material and along the cutting trajectory and/or the The split track has gaps such that the elongated damaged areas formed are positioned one after another in the longitudinal direction, and such that the damaged areas formed due to chemical changes in the workpiece material will be damaged due to physical changes in the damage. The area extends along the cutting track to the extent that adjacent common damage areas merge or overlap.